The production of artificial dentures is an art which has existed for at least several hundred years and over that period has constantly been improved to achieve the ultimate goal of maximum comfort to persons wearing such dentures and close simulation to natural dentitions. One of the principal difficulties involved in the preparation of artificial dentures comprises the arranging of artificial teeth and connecting the same to denture base material to produce finished dentures. The majority of dentures made at the present time include the connection of sets of individual artificial teeth to the denture base material and this is accomplished, in the main, by dental laboratories, but is by no means restricted to the same in that some dentists prefer to fabricate the dentures for their patients.
In general, the preparation of full dentures commences with taking impressions of both upper and lower edentulous arches, and establishing their relative position to one another both at rest and in function. These methods are described in texts and other publications, and result generally in the preparation of a "bite record" used by the dental laboratory from which a try-in is fashioned.
The impressions are taken by procedures well known to the art using alginate impression material or the like, and models of the patient's jaws and gums, known as casts are formed from setable materials such as certain gypsum material, commonly referred to as "dental stone". A baseplate is next formed upon the cast using a thermoplastic material in sheet form, by softening and adapting it over the cast. Upper and lower baseplates prepared in this manner are then used by the dentist to establish a bite record. The baseplates are introduced into the mouth of the patient, separated by soft wax which is deformed by the action of the patient's jaws as they are guided into their proper position by the dentist. The soft wax is modeled in a relatively rough labial contour of the teeth as they will be positioned in the finished denture, and the relationship between the jaws is transferred to a dental articulator which serves to hold the casts in the same relative position, as described in greater detail hereinafter. Also, certain measurements made with appropriate instruments determine the preferred vertical relation between the central, forward portions of a patient's gums on the respective jaws, known professionally as the "incisive papilla".
Individual posterior and anterior artificial teeth then are imbedded in wax material, known as "set-up wax", applied to the baseplates to conform to surfaces determined by the "bite record". Then additional wax is applied between the gingival surfaces of the artificial teeth and the baseplates in a manner to resemble natural gum contours. The foregoing operations are performed while the casts are mounted in the upper and lower bows or members of an articulator which permits relative movement between the upper and lower sets of artificial teeth formed on the casts by the foregoing procedures and thereby enables a dental technician or dentist to provide desirable occlusion and function between the artificial teeth on the respective casts. Mounting such teeth on the cast or model by the foregoing procedure requires extensive skill and is relatively time-consuming. The elimination of such substantial consumption of time is an essential objective of the present invention.
After the above procedures have been completed, the baseplates and the contoured wax material and artificial teeth mounted thereon then are removed from the casts respectively and may be tried in the mouth of the patient if desired. With the upper and lower casts attached thereto, they are then invested in suitable molding compounds, generally of a gypsum nature. The baseplate and set-up wax are removed from the hardened investment by heating and softening methods to provide a cavity into which permanent denture base material is injected or molded for connection to the ridgelap and gingival surfaces of the artificial teeth by the well-known "lost wax" process.
The foregoing procedure is generally exemplary of the methods used at present to fabricate artificial dentures. Various modified steps of the procedure occur at present, but in general, it will be seen that one of the principal difficulties arising from the procedure comprises the mounting of individual artificial teeth upon the wax substrate to which they are attached and also to provide proper occlusion between the opposed masticating surfaces of the teeth in the upper and lower dentures.
One of the improvements offered by the present invention in at least one principal aspect comprises the use of full arch upper and lower sets of artificial teeth which are integrally connected together in said sets and opposite sides of each arch formation are braced to stabilize the shape. The teeth provided in said full arch sets have certain characteristics which resemble natural teeth, while at the same time, facilitating the molding of such teeth in molds which preferably are relatively simple. In this regard, it is to be noted that the use of full arch sets of artificial teeth to form dentures is not new from a basic standpoint. Previous attempts to simplify the formation of artificial dentures have included the use of such full arch sets of artificial teeth and typical examples of the same are found in such prior U.S. Patents as U.S. Pat. No. 1,814,717 to Maizner dated July 14, 1931; U.S. Pat. No. 2,539,882 to Zilinski, dated Jan. 30, 1951; U.S. Pat. No. 2,768,440 to Elliott, dated Oct. 30, 1956; and U.S. Pat. No. 4,099,329 to Hawthorne, dated July 11, 1978.
In addition to the use of full arch sets of artificial teeth in the making of dentures as noted above, various procedures for the forming of dentures with the aid o articulators in order to attempt to minimize the amount of time consumed have been the subject matter of other prior U.S. Patents including U.S. Pat. No. 1,814,717 to Maizner, dated July 14, 1931; U.S. Pat. No. 2,171,759 to Meyer, dated Sept. 5, 1939; and U.S. Pat. No. 4,189,837 to Stele, dated Feb. 26, 1980, as well as prior British patent No. 295,768 to Perks, dated Aug. 23, 1928 and prior German patent No. 508,921 to Kantorowicz, dated Oct. 2, 1930.
Further to facilitate the formation of artificial teeth with an enamel simulating layer, prior U.S. Pat. No. 1,547,643 to Clapp, dated July 28, 1925, illustrates a form of mold and technique to accomplish this, while prior U.S. Pat. No. 1,907,923 to Willis, dated May 9, 1933, is one example of a measuring device used incidental to determining desirable bite level between artificial dentures and thereby facilitate the comfort of using the same.
The characteristics and advantages of the present invention over the techniques and apparatus presently in use, as enumerated above, are set forth below in detail.